Joint study on design, synthesis and analysis of agonists and antagonists of galanin

已知含有29个氨基酸残基的神经肽甘丙氨酸在大脑和外周具有许多生物活性。下面的研究是在“丙氨酸激动剂和拮抗剂的设计、合成和分析国际联合研究”的框架下进行的。1)在我们实验室（N.Yanaihara）采用固相技术或常规溶液法合成了23种丙氨酸相关肽。2)比较人、大鼠和猪甘丙肽对离体大鼠胰腺13.9mM糖促胰岛素释放的影响。其中，大鼠丙氨酸对葡萄糖诱导的胰岛素释放的抑制作用最强。3)人、大鼠和猪在10^<-8>M时，分别抑制GRP（14-27）刺激的胃泌素释放。其中，大鼠丙氨酸在该体系中最弱。4)人、大鼠和猪在10^<-6>M下的甘丙氨酸分别以剂量依赖性的方式抑制圆形肌肉的收缩反应。甘丙蛋白包括甘丙蛋白(1-15)-醇具有几乎等效的抑制作用。这些结果强烈表明，甘丙肽的活性部位的存在，其抑制神经诱发的环状肌肉收缩在分子的氨基末端的一半。5)甘丙肽可抑制隐神经制备引起的c-纤维反应，较高浓度（1-3muM）可部分抑制单突触反射。人丙氨酸最强，猪丙氨酸最弱。氨基端片段丙氨酸(1-15)-醇的作用很弱。6) [D-Trp^<8,9>]-甘丙氨酸(1-15)-醇和[D-Thr^6， D-Trp^<8,9>]-甘丙氨酸(1-15)-醇在体外被发现对葡萄糖刺激的胰岛素释放起拮抗剂作用，而galantide，一种由甘丙氨酸（1-13）和P物质（5-11）组成的肽，在10^<-7>M中没有表现出任何拮抗活性。特别是，[D-Thr^6,D-Trp^<8,9>]-丙氨酸(1-15)-醇在10^<-7>M时完全消除了10^<-9>M大鼠丙氨酸在离体灌注大鼠胰腺中的抑制作用。7)证实了在大鼠脑中存在并广泛分布特异性[^<125>I]甘丙肽（1-15）片段结合位点。这些结合位点也存在于一些缺乏或只有很少[^<125>I]甘丙氨酸（1-29）结合位点的区域，如海马背区、新皮层和新纹状体。8)神经肽与P物质和其他速激肽共存并相互作用，特别是与丙氨酸有关。由于甘丙氨酸及其相关肽在细胞或细胞外调节机制中的重要作用及其潜在的治疗价值，了解它们与特定受体的详细相互作用将为结构-活性研究提供有用的信息。在这次国际联合研究中，对这个问题采取了多种方法，11月在静冈县举行的研讨会取得了丰硕的成果和成功。少

The neuropeptide galanin with 29 amino acid residues has been known to have numerous biological activities, both in the brain and in the periphery. The following studies have been carried out under International Joint study on Design, Synthesis and Analysis of Agonists Antagonists of Galanin.1) Twenty-three galanin-related peptides were synthesized by solid phase technology or conventional solution method in our laboratory (N.Yanaihara).2) Effects of human, rat and porcine galanins on 13.9mM glucose-stimulated insulin release were compared on glucose-induced insulin release in isolated rat pancreas.Among them, rat galanin showed the highest inhibition of glucose induced insulin release.3) Human and rat galanins as well as porcine galanin at 10^<-8>M inhibited GRP(14-27) stimulated gastrin release, respectively. Among them, rat galanin was the weakest in this system.4) Human and rat galanins as well as porcine galanin at 10^<-6>M suppressed the contractile response of the circular muscl … More e in a dose dependent manner, respectively. The galanins including galanin (1-15)-ol showed nearly equipotent inhibitory effect. These results suggest strongly the existence of the active site of galanin for its suppression of neurally-evoked circular muscle contractions in the amino-terminal half of the molecule.5) Galanins depressed the c-fiber response evoked by saphenous never preparation 0.01muM and higher concentrations (1-3muM) partially inhibited the monosynaptic reflex. Human galanin was the most potent and porcine galanin was the weakest. The amino-terminal fragment, galanin(1-15)-ol showed very weak effects.6) Both [D-Trp^<8,9>]-galanin (1-15)-ol and [D-Thr^6,D-trp^<8,9>]-galanin (1-15)-ol were found to act as antagonist on glucose-stimulated insulin release in vitro, while galantide, a peptide comprising galanin (1-13) and substance P(5-11), at 10^<-7>M did not show any antagonistic activity in this system. Especially, [D-Thr^6,D-Trp^<8,9>]-galanin (1-15)-ol at 10^<-7>M completely abolished the inhibitory effect of 10^<-9>M rat galanin in the isolated perfused rat pancreas.7) The existence and widespread distribution of specific [^<125>I] galanin (1-15) fragment binding sites in the rat brain was demonstrated. These binding sites were also present in several areas lacking or having very few [^<125>I] galanin (1-29) binding sites, such as the dorsal hippocampal formation, the neocortex and the neostriatum.8) Coexistence and interaction of neuropeptides with substance P and other tachykinins, with special reference to galanin were demonstrated.Because of the importance of galanin and the related peptides in the role of cellular or extracellular regulatory mechanisms and their potential therapeutic value, and understanding of their detailed interactions with the specific receptor would provide useful information for structure-activity study. A variety of approach to this problems have been performed in this international joint study, And Symposium help in November in Shizuoka was really fruitful and successful. Less